Greek Gnostic Amulet

3rd-5th century AD. An oval black stone amulet with an engraved image of a man with scorpion tail, carrying a two-headed goat on his shoulders; pierced for suspension. 11.1 grams, 36mm (1 1/2"). From the property of a London gentleman; thence by descent; previously in an important private Mayfair, London collection, acquired after 1970. [No Reserve]
Condition Report: Fair condition.